Jean Baillaud, the deputy military chief of the UN peacekeeping mission in DRC known by its French acronym MONUSCO, said the operation was being conducted jointly with Congolese troops.

“Our combat helicopters have inflicted losses in the ranks of the ADF (Allied Democratic Forces) and the operations are continuing,” he said.

It was the first time that the UN mission had engaged in military cooperation with the Congolese since February, when it was suspended after DRC authorities named two generals accused of gross human rights abuses to oversee joint operations.

“MONUSCO attacked the ADF with combat helicopters in the depths of Semuliki”, a village near the Ugandan border, Congolese military spokesman Mak Hazukay said.

The ADF launched a rebellion against Uganda’s President Yoweri Museveni more than 20 years ago, but were forced to pull back into the DRC.

Active in the east since 1995, the movement is accused of serious and repeated human rights violations while financing its activities by trafficking in tropical timber.

The United Nations, which maintains a peacekeeping mission of almost 20,000 troops and police in the vast central African country, accuses the ADF of killing more than 500 civilians in massacres and attacks in DR Congo’s Beni territory and the Ituri region since October 2014.

Since last September, ADF forces have been blamed for a series of attacks with automatic weapons on National Highway 4, between Beni and the frontier with Ituri province to the north.

The rebels have targeted civilian vehicles and passersby as well as army outposts.

Like the rest of eastern DRC, the Beni region has been torn by conflict for more than 20 years.

The fighting is fuelled by ethnic differences and claims to land, along with bids for control over valuable natural resources and rivalry between regional powers.